JPS63167083A - Motor compressor unit - Google Patents

Abstract

A motor-compressor unit comprising a vibration motor having two or more coils around a stator core (1), parallel to which is arranged a magnet (3,4) with a stator part (2A,2B) above it, one of the poles of this magnet being directed to the core and circularly bent air gaps being present between the stator core and the stator part, while slide elements (7,8,9,10) of an armature (11,12) traverse in these air gaps a part of an arc of a circle and the armature is rotatable about a motor shaft (13), this armature (11,12) being coupled with a piston body (16) linearly movable in a cylinder (17), which piston body (16) can vary with one side the volume of a compression space (21) with inlet and outlet valves and can vary with its other side the volume of a gas spring space (24), the gas spring space (24) being solely provided with an inlet valve (23), which adjoins the same medium supply as the inlet valve (19) of the compression space (21) and at nominal power and nominal delivery pressure and suction pressure the volume of the gas spring space (24) exceeds that of the compression space (21) by such an amount that the spring stiffness of the gas in the gas spring space (24) is equal to the spring stiffness of the gas in the compression space (21), while the piston body (16) performs during operation a vibration about a central position corresponding to the central position of the armature (11,12).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has two or more coils around a stator core, a stator portion and a magnet are arranged parallel to the stator core, and one of the magnetic poles of the magnet is directed toward the core. In addition, an arcuate curved gap is formed between the stator core and the stator portion, and the sliding element of the armature is moved along a part of the arcuate path within these gaps, and the armature is freely rotatable around the motor shaft. , and this armature is connected to a piston body that moves linearly within the cylinder, and this piston body is
The present invention relates to a motor compressor unit capable of varying the volume of a compression space with inlet and outlet valves on one side and of a gas spring space on the other side.

A motor compressor unit of this type is described in European Patent Publication No. 155057. In this known motor-compressor unit, the oscillatory periodic rotation of the armature is converted by means of a transmission into a linear reciprocating movement of a piston-shaped piston body. Such a motor-compressor unit constitutes a spring-mass system, the spring being constituted by the gas pressure on both sides of the piston body, and the mass being constituted by the mass of the piston body and the mass of the moving parts of the motor.

The aim of the invention is to obtain a motor compressor unit as described above which operates with optimum efficiency. The invention is based on the recognition of the fact that one of the requirements for optimum efficiency is that the piston body reciprocates about a center position approximately equal to the center position of the armature of the motor.

To achieve this objective, the motor compressor unit of the present invention is provided with only an inflow valve in the gas spring space;
This inlet valve is connected to the same medium supply source as the inlet valve of the compression space, and at nominal power and nominal delivery and suction pressures, the volume of the gas spring space is such that the spring stiffness due to the gas in the gas spring space is equal to the gas in the compression space. The piston body is made larger than the volume of the compression space by an amount equal to the spring stiffness of the piston, and the piston body is configured to periodically vibrate around a center position corresponding to the center position of the armature during operation. This configuration provides the motor compressor unit of the invention with optimum efficiency at nominal operating conditions. Small deviations from the nominal operating conditions only slightly shift the central position of the movable piston, and even in this case a reasonable efficiency is ensured. The effect of gas leakage from the gas spring space into the suction space along the piston can be compensated for by drawing gas along the inlet valve, which makes it possible to obtain a stable condition of the piston body.

Optimal conditions in terms of efficiency are obtained when the motor is driven at a frequency corresponding to the natural frequency of the spring-mass system. However, in practice the delivery and suction pressures vary when the motor compressor unit is used, for example, in a refrigeration system. It is considerably influenced by the spring stiffness of the gas in the compression space and the gas spring space, the supply pressure, and the suction pressure, and the natural frequency of the device system also changes with fluctuations in the supply pressure and suction pressure. Maximum efficiency is therefore almost never achieved without control.

The frequency at which the motor operates can be electronically controlled to match the changing natural frequencies of the equipment system.

However, by adjusting the suction pressure and supply pressure that act on the spring stiffness of the gas in the compression space and gas spring space, the natural frequency of the device system can be kept almost constant, and the center position of the vibrating system can be kept unchanged. I found out that I could do it by putting it in place.

In a preferred embodiment of the motor compressor according to the invention, the suction and/or delivery leads are provided with controllable restrictions to reduce the suction pressure when the delivery pressure increases or to reduce the delivery pressure. The structure is such that control can be performed to increase the suction pressure when the suction pressure is increased.

The invention is based on the recognition of the fact that when the delivery pressure in a compression space increases, the spring stiffness of the gas in this space increases. The spring stiffness decreases when the suction pressure decreases. Combining these phenomena keeps the spring stiffness and natural frequency of the system approximately constant.

Both suction pressure and feed pressure can be adjusted, but only suction pressure is adjusted in response to changes in feed pressure, and when feed pressure increases, suction pressure is decreased, and feed pressure decreases. It is advisable to increase the suction pressure when doing so. For motor compressor units where the natural vibration of the movable system and slight fluctuations in the center position are expected, a controllable restriction part is installed only in the suction IJ-domain to maintain the suction pressure constant regardless of the feed pressure. It is good to have a configuration.

Further, in preferred embodiments of the invention, both the suction and delivery leads contain controllable restrictions;
Suction pressure and delivery pressure are each independently maintained at a constant low pressure.

Next, preferred embodiments of the present invention will be described with reference to the drawings.

For a description of the motor compressor shown diagrammatically in FIGS. 1 and 2, reference is made to EP 155 057. The motor compressor has a stator core 1 and stator parts 2A and 2B. A gap is provided between the core 1 and the portion 2, and magnets 3 and 4 are placed in this gap, with one of the magnetic poles facing the core. Two further coils 5 and 6 are wound around the stator and connected to an alternating voltage.

Four sliding elements 7.8 and 9.10 are provided in the gap between the core 1 and the stator part 2 and are rotatable about the motor shaft 13 via the armature parts 11 and 12.

Parts 11 and 12 are connected via part 14 and a Scottish yoke structure 15 to a piston 16 which is housed in a cylinder 17 and is capable of linear reciprocating movement.

A plate 18 is provided on one side of the cylinder 17, and an inlet valve 19 and an outlet valve 20 are provided on this plate,
Allowing gas to flow into and out of the compression space 21.

A gas spring space 24 is delimited by a plate 22 provided with an inlet valve 23 on the other side.

The inlet valves 19 and 23 are connected to a common suction lead pipe 25 through which the working medium can flow into each space.

The outflow valve 20 is connected to a feed lead pipe 26, which is supplied with working medium compressed by a compressor.

The lead pipes 25 and 26 are, for example, part of a cooling circuit,
The circuit is equipped with a capacitor (not shown), a choke valve and an evaporator.

A controllable restriction 27 is provided in the suction lead pipe 25.

Next, the operation will be briefly explained. The alternating current flowing through the coils 5 and 6 causes the armature part 11.12 to rotate in oscillation about the motor shaft 13. The sliding elements or sliding parts 7, 8, 9, 10 of the armature shown in the drawings are in a central position, one half of each sliding part entering the gap between the stator core and the stator part, and the other half entering the gap between the stator core and the stator part. This void tends to deviate.

During operation, the alternating magnetic field produced by coils 5 and 6 is superimposed on the magnetic field of permanent magnets 2A and 2B. Therefore, each slide part? , 8, 9.10 take alternately high and low values. The magnets 3 and 4 are magnetized so that their magnetization directions are the same, and the coils 5 and 6 have two slide portions 7, 8, or 9 arranged diagonally opposite each other so that the direction of rotation of the current flowing through these coils is the same. 10 are simultaneously subjected to a high magnetic flux and these sliding parts are drawn into the air gap, while the remaining two sliding parts are subjected to a low magnetic flux density and are located outside the air gap. This causes the slide portion and armature portion to vibrate.

Armature vibrations are transmitted to the piston 16 via the armature section 14 and the Scottish yoke structure 15. One side of the piston 16 influences the volume of the compression space 21 and the other side influences the volume of the gas spring space 24. The gas in these two spaces acts as two springs and forces the piston and the parts connected to it, such as the yoke 15 and the sliding part 7. 8. 9.1
An actual spring-mass system is obtained in which the masses of the armatures 11 and 12 having zero are the spring-system masses. The piston 16 then reciprocates about a predetermined center position, and this reciprocation depends on the electrical power supplied to the motor, the delivery and suction pressures, and the spring stiffness of the compression space and the gas spring space.

The electric motor is at optimum efficiency when the armature oscillates around a central position in which the sliding parts 7, 8 and 9° 10 are located only half in their respective air gaps, and the other half is located outside this air gap. Operate. The optimal center position of the piston 16 is fixed when the armature is secured to the piston 16, and this position makes the gas spring space 24 slightly larger than the compression space, so that the spring stiffness of the gas in the two spaces is approximately the same. According to the present invention, the cinder is configured so that: Any leakage along the piston etc. is compensated for by having only an inlet valve in the gas spring space, so that the suction pressure on both sides of the piston is equal.

In this way a spring-mass system is obtained which oscillates about a central position. Such a motorized compressor has optimum efficiency when it has a motion about a central position and is driven by a motor at a frequency that approximately corresponds to the resonant frequency of the spring-mass system.

In such compressors, the delivery pressure and the suction pressure vary depending on the conditions occurring in devices connected to the delivery and suction valves, such as the cooling circuit, in which the pressure varies with the temperature of the outside air.

During fluctuations in the delivery and suction pressures, the spring stiffness of the gas in the compression space and the gas space also changes, and the resonant frequency of the device also changes. At this time, if the feeding pressure and suction pressure are matched,
It has been found to keep the effective spring stiffness and resonant frequency equal.

For this reason, in the compressor shown in the drawings, a controllable restriction part 27 is housed in the suction lead pipe, and this restriction part is controlled based on the pressure in the delivery lead pipe 26, so that when the delivery pressure increases, the restriction part is throttled. control to reduce suction pressure. In this way, the spring stiffness and the resonant frequency remain unchanged so that under all operating conditions the motor compressor operates at optimum conditions and the optimum center position of the piston also remains unchanged. The degree of relative control of delivery and suction pressures depends on the size of the compressor. Diameter 25m
In a compressor with a cylinder bore of m and a piston stroke of 14 ml1, both the suction lead pipe 25 and the delivery lead pipe 26 accommodate controllable restrictions 27 and 28, respectively, at values of the delivery pressure P. In this case, the restriction 27 controls on the basis of the pressure in the suction lead and maintains this pressure at a constant low value, for example equal to the minimum pressure that occurs during operation of the evaporator of the cooling circuit connected to the compressor. The restriction part 28 is the feed lead pipe 26
and maintain this pressure at a constant low pressure, for example equal to the condensing pressure at normal ambient temperature of the cooling medium used in the cooling circuit connected to the compressor. Since in this embodiment the compressor operates at constant delivery and suction pressures, the resonant frequency is always the same and therefore the compressor unit operates at maximum efficiency under all operating conditions.

[Brief explanation of the drawing]

1 is a diagrammatic cross-sectional view of a preferred embodiment of a motor compressor according to the invention; FIG. 2 is a cross-sectional view taken along line II-n in FIG. 1; and FIG.
1 is a diagrammatic cross-sectional view of a second embodiment of a motor compressor according to the invention; FIG. 1... Stator core 2^, 2B... Stator part 3.4... Magnet 5.6... Coil? , 8, 9.10... Slide elements 11, 12... Armature portion 13... Motor shaft 14... Portion 15...
・Scottish yoke structure 16...Piston 17...Cylinder 18
, 22...play) 19.23...inflow valve 20...outflow valve 21...compression space 24...gas spring space 25...gas suction lead pipe 26...feeding lead pipe 27.28...Limited Part Patent Applicant N.B.Philips Fluiran Penfabriken Shiri

Claims (1)

[Claims] 1. It has two or more coils around the stator core, a stator part and a magnet are arranged parallel to the stator core, and one of the magnetic poles of the magnet is directed toward the core, and the stator core an arcuate curved air gap is formed between the motor and the stator part, the sliding element of the armature is moved along a portion of the arcuate path within these air gaps, and the armature is rotatable around the motor shaft; The armature is connected to a piston body that moves linearly within the cylinder and changes the volume of a compression space with an inflow and an outflow valve on one side and a gas spring space on the other side. In a motor compressor unit which can be used, the gas spring space is provided with only an inlet valve, which is connected to the same medium supply source as the inlet valve of said compression space, and which, at nominal power and nominal feed and suction pressures, has no gas The volume of the spring space is made larger than the volume of the compression space by an amount such that the spring stiffness due to the gas in the gas spring space is equal to the spring stiffness of the gas in the compression space, and during operation, the piston body is set at a center position corresponding to the center position of the armature. A motor compressor unit characterized by having a configuration in which periodic vibration occurs around the motor compressor unit. 2. Provide a controllable restriction section in the suction and/or delivery lead pipe to control the suction pressure to decrease when the feed pressure increases or to increase the suction pressure when the feed pressure decreases. The motor compressor unit according to claim 1, characterized in that the motor compressor unit is configured to be able to perform the following operations. 3. The motor compressor unit according to claim 1, characterized in that a controllable restriction part is provided only in the suction lead pipe, and the suction pressure is maintained constant regardless of the feed pressure. 4. A controllable restriction part is housed in both the suction lead pipe and the delivery lead pipe, and the suction pressure and the delivery pressure are each independently maintained at a constant low pressure. The motor compressor unit according to item 1.